I'm no expert, but I'm pretty sure we have a good understanding of historical weather based on various natural indicators in the earth's crust. You can read abo

I'm no expert, but I'm pretty sure we have a good understanding of historical weather based on various natural indicators in the earth's crust. You can read about some of the techniques on NOAA.gov (https://www.ncdc.noaa.gov/news/how-do-scientists-study-ancient-climates https://www.ncdc.noaa.gov/news/how-do-scientists-study-ancie...)